De-colonization

Southeast Asia went through many changes between the 1940s and the late 1960s. SE Asia was reeling from European colonialism when the Japanese invaded in the late 1930s and early 1940s. Many countries accepted the Japanese as friends rather than as invaders. This happened in Thailand where the British and Japanese helped the Thai expand their territorial borders. Resistance movements rose up and fought against the control of the Japanesee. Again Thailand is an example where this happened.
After the end of the Second World War, the Japanese lost the war and now SE Asia went through a hard de-colonization period, where European powers left and states fought for their independence. However, this idependece came at a price that included violence, shortages, disorder, chaos, and a great loss of life. Most went through stages of totalitarianism and various forms of democracy.
SE Asia became a battleground between democracy and capitalism. The French left, in Vietnam, and the Americans took over after the 1954 Geneva Accords. The United States backed Diem, who was later killed and then a long war enused in Vietnam, which the US eventually lost. South Vietnam was never seen as a viable seat of government by the North who saw them as lackeys for the Americans. The US eventually left and a civil war ensued. A major theme of this period was Marxist-Leninism, which many countries adopted; they saw it as a major philosophy against one colonial empire after another. American influence spilled over into Vietnam during the 1970s first with B-52 bombing raind and eventual invasion my US ground forces.
Most people are aware of Pol Pot who killed three million Cambodians. The United States supported Lon Nol (he was corrupt and had corrupt officers), Pol Pot (and the Khmer Rouge) took over and ran the civilians out of the city and many became followers of Pol Pot who wanted to unite all of SE Asia into one large collective.
Norodom Sihanouk was a popular figure in Cambodia whose goal was a free and neutral state. However, he was an incapable leader and the people paid a high price with the arrival of Pot and the Khmer Rouge. Sihounak was eventually overthrown by Cambodian military generals; he was forced to live in exile in China. He eventually turned face and supported Pot. The Vietnamese invaded in 1978 and forced the Khmer Rouge out of Cambodia. He had lofty goals for his country, which he was ubable to make a reality, and as a result, many Cambodians suffered for his ineptitude.